When asked to name the great conquerors of history, chances are you’ll think of a younger man. Alexander the Great was just twenty-five when he defeated the great King of Persia. Scipio Africanus – the Roman general who finished off Hannibal – was also twenty-five when appointed directly by the People’s Assembly to his command. Napoleon was twenty-six when he was made commander of the French armies in Italy, and he returned to France the following year a hero.

One conqueror you probably would not name is Claudius, the Roman emperor (41-54) who launched an invasion of the British isles in 43 AD. Turning fifty-three that year, he had never commanded an army before. Since childhood he had suffered from a nervous disorder that made him stammer, drool, and jerk his neck. He limped around and had trouble controlling his laughter. According to the biographer Suetonius, Claudius’ own mother regularly called him “a freak of man, not finished by Nature but only begun.” If she wanted to put somebody down, she’d say he was stupider than Claudius.

The imperial family worked hard to keep Claudius hidden. When Claudius put on the toga of manhood – normally a grand ceremony – he was forced to do so at midnight, and nobody was invited. As Augustus wrote to his wife (and Claudius’ grandmother) Livia: “The public must not be given a chance of mocking him – and us.”

Unlike others of his rank, Claudius was given no training in oratory and warfare. Instead, he spent his days in his mother and grandmother’s house, drinking, dicing, and writing up voluminous histories in Greek and Latin. Only when Caligula succeeded Tiberius as emperor in 37 AD did Claudius, now forty-five-years old, join the Senate, when he briefly served as consul with Caligula. For some, the sudden promotion must have seemed like another one of Caligula’s cruel jokes. Remember that Caligula was said to have wanted to make his favourite race horse a consul too!

Yet it is Claudius’ very implausibility as a conqueror – or even as an emperor – that took him to Britain. When Caligula was assassinated in 41 AD, it was initially only the elite Praetorian Guard, in charge of the emperor’s security, who supported Claudius. In the Senate some spoke of restoring the old Republic, while a number of others thought that they themselves would make a better emperor than Claudius. Despite eventual confirmation by the Senate of his succession as princeps, Claudius’ early hold on power was fragile: alongside his physical idiosyncrasies, unlike his two predecessors, he had not been adopted into Augustus’ branch of the family and so lacked the magical names of “Julius” and “Caesar.” An attempted coup against Claudius in 42 failed, but left him even more isolated and looking to distract attention from its nasty aftermath.

When Caligula had become emperor at the age of twenty-four he was also interested in adding to his resume and had seen an opportunity to annex at least part of Britain. Trade and diplomacy since the time of Augustus had gradually brought its peoples more fully into the Roman world. Turmoil among their leaders had driven some to seek out increased Roman intervention. And the elderly king of the powerful Catuvellauni, Cunobelin (Shakespeare’s Cymbeline), was approaching death – creating a perfect opportunity for a Roman takeover.

Caligula’s visit to Gaul and Germany in 39 and 40, along with the creation of two new legions, was almost certainly a prelude to a planned invasion. But, in the end, it was called off. Famously, Caligula’s soldiers were instead made to gather shells as booty on the coast of the English Channel.

By 43 AD King Cunobelin was dead. His sons were growing defiant, and another king, Verica, had fled Britain and begged Claudius for help. It became the ideal pretext for Claudius to launch his war. Aulus Plautius, a capable general and loyal to Claudius, was sent over first with a large army of four experienced legions. Driving the resisting Britons back to the Thames – while cutting deals with many others – Plautius then summoned Claudius to lead the final assault on the Catuvellaunian capital at Camulodunum (modern Colchester).

Claudius duly appeared with a large entourage, including his favourite Greek physician and – if we can trust the historian Cassius Dio – some war elephants. Meeting up with Plautius, Claudius briefly put under siege a poorly defended Camulodunum, took the settlement, and afterward received surrender from a number of British kings, even perhaps including a ruler from the Orkneys!

The emperor then travelled back to Rome and began hyping up his great victory. He and his infant son were awarded the new name “Britannicus.” The Senate voted Claudius a triumph, the grand victory parade that wound its way through the streets of Rome, with exotic captives on display. Lavish games were held in conjunction with the triumph. Claudius, putting on a military cloak, even presided over an elaborate re-enactment of the fall of Camulodunum. A victory arch went up on the busy Via Flaminia, greeting visitors to Rome from the north.

Contemporary writers did their part too. A Spanish geographer proclaimed Claudius to be “the greatest of emperors” because he was opening up Britain for “greater exploration.” The philosopher Seneca, in exile in Corsica and hoping for a reprieve, wrote a treatise in which he prayed that Claudius might “open up Britain” and celebrate triumphs over nations already conquered and new ones too.

Yet in many ways all the celebration was premature. For several decades, Plautius and his successors, and the troops under them, faced great difficulties. The famous Boudican revolt was only the most catastrophic of many insurgencies. In Rome itself, it even started to be asked whether it was worth it at all to keep troops in Britain.

A longer perspective allowed later writers to put Claudius’ great “conquest” in a different light. In his biography of Claudius Suetonius tartly noted: “He made just one campaign, and a slight one at that.” By Suetonius’ account, the storms Claudius faced en route to Britain were far more dangerous than anything he faced in Britain itself. While somewhat more positive, Cassius Dio’s account is not terribly heroic either. The soldiers had to be shamed into crossing the Channel by a freed slave of Claudius. And as for Claudius himself, Dio writes: “he spent only sixteen days in Britain.”

These writers leave us asking even today: was the Roman annexation of Britain worth it for Rome? And without Claudius’ desperation for some good publicity, would it ever have happened?